A new and distinct nectarine cultivar named ‘Effie’ is described herein. The new cultivar originated from a hand-pollinated cross of Ark. 720 nectarine (female parent; non-patented; unreleased breeding genotype) x Ark. 747 peach (male parent; non-patented; unreleased breeding genotype) made in 2004 near Clarksville, Ark. This new cultivar was selected in 2008 for its potential as a fresh-market nectarine in Arkansas and the mid- to upper-southern United States. ‘Effie’ can be distinguished by its distinctly crisp non-melting flesh, mid-season ripening, medium size, attractive appearance, high red skin color, excellent white nectarine flavor, postharvest performance, and resistance to bacterial spot disease.